The only problem with that, would be to make them all competitive with each other, and still be true to the specifics of each marque's handling. To get them all to handle realistically, and still be competitive would be great, but it is a big ask. Try comparing the current BMW DTM in XMR to the current AMG DTM car, and the AMG will kill the BMW in every aspect. If it was like this in real life it may as well just be called the AMG cup, because that's all that would be there, AMG's.